1. Field of the Invention
The invention is directed to a two-lever three-function control mechanism for independently controlling the positioning of three separate hydraulic control valves.
2. Description of the Prior Art
In operating a work vehicle, such as a loader backhoe, the operator controls a plurality of work operations through manipulating various control levers that control the positioning of hydraulic control valves. The hydraulic control valves in turn regulate the flow of hydraulic fluid to hydraulic cylinders that manipulate the work implement. While using a loader the operator may also be turning the steering wheel and shifting the transmission as he loads and unloads the bucket.
The operator may be provided with a single lever that controls both raising and lowering the boom, and tilting the bucket. By moving this lever in a first plane, front-to-back, the position of the boom is manipulated. By moving this lever in a second plane, side-to-side, the bucket tilt is adjusted.
Many times the bucket maybe provided with a third function, for example a side tilt bucket or a clam shell bucket. The third function typically requires a third hydraulic cylinder and a third hydraulic control valve for controlling the positioning of this cylinder. The control mechanism for controlling the third hydraulic control valve may comprise a single control lever, such as that disclosed in U.S. Pat. No. 4,938,091, or two control levers, such as that disclosed in U.S. Pat. No. 4,389,151.
In the two control lever mechanism, shown in U.S. Pat. No. 4,389,151, it is desirable that the second control lever move with the first control lever, so that the second control lever is always close at hand when manipulating the work implement with the first control lever. The first and second levers disclosed in this patent move together in a first plane and independently of one another in parallel second and third planes. They are coupled together by a link extending between the control levers.